This invention relates to an apparatus which attaches films to the surfaces of sheet materials (hereinafter simply called boards), such as printed circuit boards, electronic circuit boards, and silicone wafers; and, more particularly, the invention relates to a vacuum film laminating apparatus which continuously supplies films and boards into a reduced-pressure chamber and attaches films to each board in the chamber.
A conventional reduced-pressure film laminating apparatus, such as disclosed in Japanese Examined Patent Publication No. 53-31670 (1978), places the whole film laminating apparatus containing a roll of film (hereinafter referred to as a film roll) in a reduced-pressure chamber, and provides a board loading opening and a board unloading opening in the walls of the reduced-pressure chamber. Each opening has a pair of pressure rolls made of, for example, elastic materials which isolate the inside of the reduced-pressure chamber from the outside, making it possible for the boards to be introduced into and removed from the chamber. This reduces fluctuations in the degree of vacuum of the reduced-pressure chamber when boards are transferred into and out from the chamber and assures the efficiency of attaching films to boards at a reduced pressure.
Since this conventional vacuum film-laminating apparatus disposes a film roll in the reduced pressure chamber, the chamber cannot be made smaller. Further, when a new film roll is loaded in the reduced-pressure chamber, it takes a long time to reduce the chamber pressure down to a preset degree of vacuum. Furthermore, keeping a film roll for a long period of time under a vacuum condition may cause its quality to vary.
When boards are loaded into the reduced-pressure chamber, the pressure-rolls may frictionally cause dust to be deposited on the surfaces of the boards. The dust on the board surfaces may make film adhesion incomplete in the film lamination process and may damage board surfaces when they are compressed to be unloaded.
When the pressure rolls are worn out due to friction between the rolls and the boards, the hermetic sealing of the chamber is broken and the chamber cannot maintain a preset reduced pressure. This requires frequent replacement of pressure rolls; and, consequently, this makes it difficult for the conventional vacuum laminating apparatus to respond to the demands imposed on a high vacuum device.
Japanese Examined Patent Publication No. 53-31670 (1978) also discloses an embodiment in which the film roll is disposed outside the reduced-pressure chamber. This embodiment is necessarily equipped with means to feed film sheets into the reduced-pressure chamber, in addition to the provision of said board loading and unloading openings. This film feeding unit has a pair of pressure rolls made of elastic material to feed film sheets there through. However, this embodiment cannot avoid the problems which may be caused by friction between the boards and the pressure rolls.
The main purpose of the present invention is to provide a reduced-pressure film-laminating apparatus which can form a clean reduced-pressure chamber having a desired degree of vacuum in a short time and continuously attach films to each board in the reduced-pressure chamber.
Another object of the present invention is to provide a reduced-pressure film-laminating apparatus which continuously supplies boards and films into the reduced-pressure chamber and attaches films to the boards in the chamber without damaging them.
To realize the aforesaid objects, the reduced-pressure film-laminating apparatus in accordance with the present invention comprises:
board transfer means for transferring a plurality of boards at preset intervals;
film transfer means for forming film sheets on a base film at the same intervals as the boards are transferred by said board transfer means, wherein these intervals on the base film are treated as processing areas between boards;
a reduced-pressure chamber having a board loading port, a film loading port, laminating means for attaching films to each board on said base film in said chamber, and a board unloading port which ejects the laminated boards;
first shutter means providing a shutter for each of said board loading and unloading ports of the reduced-pressure chamber to open and close the port;
vacuum means for evacuating the reduced-pressure chamber when said respective shutter means close;
second shutter means providing a shutter for said film loading port on said reduced-pressure chamber;
detecting means for detecting the extent of a processing area between boards on the base film to the shutter section of said film loading port; and
control means for operating said second shutter means of said film loading port, said board loading port, and said board unloading port according to the result of detection by said detecting means, thereby to close the shutters, for evacuating the reduced-pressure chamber to a preset degree of vacuum, and for turning on the laminating means.
In accordance with the present invention, the reduced-pressure film-laminating apparatus can supply films into the reduced-pressure chamber without contaminating the film sheets, and it can evacuate the reduced-pressure chamber to a desired degree of vacuum and attach films to clean boards.